What is the effect of light pollution on humans and/or animals?

"We rarely stop to think that the night is necessary and good for life. Therefore, we do not realise that protecting the night sky is a valuable step to conserving bio-diversity. Most people think that, as we sleep at night, the rest of the species do the same, with a few exceptions, so it is of no concern if we send out a little light into the night time environment. A crass error. Naturalists know (and it would help if they said so more often) that the biological activity of our fauna is more intense at night than during the day and that this fauna needs the night for their normal activities.
Pere Horts
Deputy Chairman of Cel Fosc. Catalonia. Spain"

Discuss some aspect where there is actual factual scientific data (use .edu sites).
1. Give an overall summary of the effect
2. Choose a specific area and summarize what was found in that area by research.

Minimum 500 words.